The publishing industry is buzzing with reports that "Harry Potter" author J.K. Rowling has made the switch from wizards to killers, after signing a new deal to write a book for adults.

On Friday, Rowling (@jk_rowling) tweeted: "As you may have heard, I have a new book out later this year. Very different to Harry, although I've enjoyed writing it every bit as much."

Publishers Little, Brown announced it had snapped up the latest project from Rowling -- one of the world's best-selling authors -- who said she was looking forward to "this new phase of my writing life."

"The freedom to explore new territory is a gift that Harry's success has brought me, and with that new territory it seemed a logical progression to have a new publisher," she said in a statement.

Rowling's choice of Little, Brown publisher David Shelley as editor has led to fevered discussion as to whether her new work will take the form of a murder mystery.

"The rumor is that it's a crime thriller, and that it could be set in [her adopted home of] Edinburgh; there's no smoke without fire," Philip Jones, deputy editor of trade paper The Bookseller, told CNN. "Her new editor, David Shelley, is known for his work with crime thrillers."

Shelley also works with popular crime writers Val McDermid and Mark Billingham.

After news of the deal broke, McDermid (@valmcdermid) tweeted: "Nice to see that JK Rowling has such good taste in editors..." suggesting to Billingham (@MarkBillingham): "Do you think her choice [of David Shelley] means she's writing a thriller/crime novel?"

She later added: "It's a reasonable speculation that it's a mystery, since that's what David Shelley does so well..."

And fellow crime writer Ian Rankin (@beathhigh) tweeted "Wouldn't it be funny if JK Rowling's first novel for adults turned out to be a crime story set in Edinburgh?"

Rankin, author of the best-selling "Rebus" novels, themselves set in the city, jokingly added: "Might explain why she left the neighbourhood (me, [Alexander] McCall Smith, [Kate] Atkinson near-neighbours) and moved across town.

"She's certainly a fan of the traditional whodunnit."

Jones said whatever form the new book takes, it is certain to provide a much-needed shot in the arm for the publishing industry.

"What the book trade needs desperately is 'event books' -- high profile titles by famous authors, which get people going into bookshops to buy them, or even just to look at them, and then end up buying others.

"But they are few and far between -- they come up once or twice a year. This is the event book to blow all other event books out of the water."

He said that the book's simultaneous publication as an ebook would be closely watched for clues to the health of the ebook market, and its impact on the "real" book market.

"That has never happened before, either with Harry Potter or with other 'event titles,' and now that ebooks make up a 20th of the market, it will be fascinating to see if that has an impact -- it really could be a game-changer."

Jones said it was unlikely Rowling would be able to repeat the massive success of the "Harry Potter" books, the tales of a young wizard which have sold more than 400 million copies worldwide, and sparked a film franchise and a merchandizing empire.

"I don't think it will be as big as Harry Potter, but Harry Potter was built up slowly over time -- this, as far as we can tell from the press release, is a single book, and an adult book, so she will be looking for a new audience, and they may take some convincing."

But he said it made sense for Rowling to make a fresh start, with her switch to writing for "grown-ups."

"Her writing has grown up, as have her readers: Most of the youngsters who read the first Harry Potter books when they came out are adults now, so she has a ready-made audience."